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HURRICANE SANDRA DISCUSSION NUMBER  13
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP222015
200 PM MST THU NOV 26 2015

Sandra's satellite presentation features a large CDO and impressive
outflow in the northern semicircle. However, increasing shear has
begun to restrict outflow in the southwestern quadrant. The initial
intensity has been lowered to 105 kt based on a blend of the latest
Dvorak Final-T and CI numbers (T5.0/6.0) from TAFB and SAB. Further
quick weakening is expected as the shear is forecast to increase to
about 35 kt in 24 hours and 50 kt by 48 hours. This should result in
Sandra's low-level circulation becoming decoupled as the mid- and
upper-level warm core is sheared off to the northeast. The new NHC
intensity forecast closely follows the latest SHIPS model guidance,
and shows Sandra weakening to a remnant low by 48 hours. A 72-h
point is shown for continuity, but the low-level center of Sandra
should dissipate quickly after it moves inland over mainland Mexico
after 48 hours.

Sandra has moved a little to the left of the previous forecast
track, with an initial motion of 360/10. The track model guidance
has shifted to the left this cycle, and keeps Sandra on a northward
heading for the next 12 to 24 hours before turning north-
northeastward between a mid-level ridge over Mexico and a broad
deep-layer trough over western North America. The new NHC track has
been adjusted 30-45 n mi to the left given the initial motion and
the trend in the guidance, and now brings the center of a weakening
Sandra closer to the southern tip of the Baja California peninsula
in 36-48 hours. The NHC forecast is close to the new latest multi-
model consensus.

Given the updated forecast, the government of Mexico has issued a
tropical storm watch for the southern tip of the Baja California
peninsula from Todos Santos to Los Barriles.

Note that the remnant mid/upper-level moisture associated with
Sandra will contribute to a significant precipitation event
expected to occur over portions of the south-central United
States this weekend. For more information on this event, please see
products from the NOAA Weather Prediction Center and local NWS
Weather Forecast Offices.

FORECAST POSITIONS AND MAX WINDS

INIT  26/2100Z 16.8N 110.1W  105 KT 120 MPH
 12H  27/0600Z 18.1N 110.2W   85 KT 100 MPH
 24H  27/1800Z 19.8N 110.1W   65 KT  75 MPH
 36H  28/0600Z 21.8N 109.5W   45 KT  50 MPH
 48H  28/1800Z 24.2N 108.7W   30 KT  35 MPH...POST-TROP/REMNT LOW
 72H  29/1800Z 27.0N 107.5W   15 KT  15 MPH...POST-TROP/INLAND
 96H  30/1800Z...DISSIPATED

$$
Forecaster Brennan

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